A joint between two aircraft structural members that is loaded in tension, for example a cargo tie-down on an aircraft floor that in use exerts tension loads on a joint between two structural members in an underfloor frame, requires additional features to support the joint. Typically, support of the joint would be provided by separate machined metallic fittings that are mechanically fastened between the structural members. However, these metallic fittings are heavy and bulky. Furthermore, adding the metallic parts to the joint between the structural members requires additional manufacturing time that adds cost to the structure. Still further, metallic fittings added to a joint between two structural members of a frame often do not provide the level of support to the joint desired.
There are composite fittings that are designed to handle the tension loads at the joint between two structural members. However, these composite fittings require separate metallic parts, such as radius blocks, to distribute the loads exerted on the joint efficiently into the fitting. Adding the metallic parts to the joint between the structural members adds weight to the structure. Additionally, today's metallic and composite fittings are poor at absorbing energy of a compression load.
There is a need for a single fitting that combines tension, shear and a high level of energy-absorbing capability in a single structural element.